Temperature controller for fluid in an apparatus having a plurality of operation cycles

ABSTRACT

A temperature controller for controlling the temperature of water in a washing machine during each one of the operation cycles of the washing machine. A separate circuit for each operation cycle of the machine is provided for producing a signal representative of a selected water temperature during that cycle. A single temperature indicating device indicates the water temperature during each one of the cycles and a single thermistor circuit produces a signal representative of the actual water temperature during each one of the cycles. The signal from the temperature selection circuit and the thermistor circuit is applied to a comparison means which produces an output signal dependent on a predetermined relationship of the two input signals and causes water of a temperature required to reach desired water temperature to be added to the washing machine. A programmer selects the cycle in which the washing machine is to operate and also actuates the temperature selection circuit which is to control the water temperature of the operation cycle selected. Actuation of any one temperature selection circuit produces an output which blocks any output from the other temperature selection circuits to the comparison means so that there will be no interference with the comparison of the signal from the actuated temperature selection circuit and the signal from the thermistor circuit.

United States Patent [111 3,875,424

Hopkins Apr. 1, 1975 TEMPERATURE CONTROLLER FOR FLUID IN AN APPARATUSHAVING A PLURALITY [57] ABSTRACT OF OPERATION CYCLES A temperaturecontroller for controlling the tempera- [75] Inventor: Charles L HopkinsNOW/00d OhiO ture of water in a washing machine during each one of theoperation cycles of the washing machine. A sepa- ASSlgneei MCGIaWEdlSm py Elgim rate circuit for each operation cycle of the machine is providedfor producing a signal representative of a se- [22] Filed: 27, 1973lected water temperature during that cycle. A single temperatureindicating device indicates the water teml l PP 391374 perature duringeach one of the cycles and a single Re'aed Us Appncation Datatgermistolr circuit produces a signal reprfisentatige [pf I t e actuawater temperature urmg eac one o t e [62] g::' g i? EH37 1972 cycles.The signal from the temperature selection cir' cuit and the thermistorcircuit is applied to a compari- 52 us. Cl. 307/117 219/497 mans whichProduce? 9 Sign?" l i [51] Int. Cl. Htilh 37/26 on a predetermmedrelatlonsh'p of the p [58] Field of Search IIIIIIIIII u 307/! I6. H7;219/494, nals and causes water of a temperature required to 219/497 499!486 reach desired water temperature to be added to the washing machine.A programmer selects the cycle in [56] References Cited which thewashing machine is to operate and also actuates the temperatureselection circuit which IS to UNITED STATES PATENTS control the watertemperature of the operation cycle 1819540 lH958 Tomi! ct 68/l2 Rselected. Actuation of any one temperature selection 21928367 M960 FTC)"circuit produces an output which blocks any output 3330270 7/1967wenncrbcr'g from the other temperature selection circuits to the :13? ct307/116 X comparison means so that there will be no interference withthe comparison of the signal from the actuated temperature selectioncircuit and the signal from the thermistor circuit.

Primary E.\'aminerRobert K. Schaffer Assistant liraminer-M. GinsburgAttorney, Agent, or Firm-Jon Carl Gealow 2 Claims, 1 Drawing Figure WASHINE MACHINE L A; z: j8 .LL i

34 36 t u t l i gLa-t l l l L I t i g t -1 p D? n D9 92 30 L kqrj/ R! 171 23 )F I .t/ I l l H l l l t 98 l m l R3 R15 R? R9 VOLTAGE a L! l i l iREGULATOR i a b mg It I 56 l R2 R8 l R111 l l vvLw 1L0! & 43 J {:13 l ll l l l l l 1 26 a- 1 l l 100 I )w I vi R5 02 g l as Q 1 I l n a l l J lL l TEMPERATURE CONTROLLER FOR FLUID IN AN APPARATUS HAVING A PLURALITYOF OPERATION CYCLES This is a division of application Ser. No. 23l.l37.filed Mar. 2, 1972 now US. Pat. No. 3,772,900 issued Nov. 20. I973.

BACKGROUND OF THE INVENTION This invention relates to a temperaturecontroller for fluid in apparatus having a number of operation cyclesand in particular to a temperature controller for water in a washingmachine. Temperature controllers for water in industrial type washingmachines typically use a different temperature control circuit for eachoperation cycle of the washing machine. These controls require aseparate temperature sensing element such as a thermistor and all of itsassociated circuitry for sens ing actual water temperature and attainingthe desired water temperature. Use of such separate thermistors andrelated circuitry, of course. requires more space and adds to the costof the washing machine. Further. present control circuits do not includecircuit means for indicating actual water temperatures to personnelmonitoring machine operation.

SUMMARY OF THE INVENTION It is an object of the invention to provide atemperature controller for fluid in an apparatus having more than oneoperation cycle in which a substantial amount of the circuitry iscommonly used to control and indicate the fluid temperature during eachdifferent operation cycle. It is a more specific object of the inventionto provide an automatic water temperature controller for a washingmachine having a plurality of operation cycles in which only a singlethermistor and a single temperature indicating device are needed forsensing and indicating the temperature of the wash water during eachoperation cycle of the washing machine.

The objects of the invention are accomplished by providing a separatecircuit for each operation cycle of the apparatus which produces anoutput signal representative of the desired fluid temperature for thatcycle and which in operative to produce the signal only dur ing the timethe cycle takes place. A single thermistor is in contact with the fluidin the apparatus and, in combination with other appropriate circuitcomponents, produces a signal representative of the actual temperatureof the fluid during each cycle. A single temperature indicating deviceis in circuit with the thermistor and visually indicates the watertemperature during each cycle.

A comparison means is arranged to receive the signal from the thermistorcircuit and the signal representative of the desired fluid temperatureduring a cycle. Depending upon the relationship of the levels of the twosignals, the comparison means is operative to produce an output signalwhich results in the adding of fluid permitting attaining the desiredtemperature to the fluid in the apparatus. The circuits producing thesignal representative of the desired fluid temperature are arranged suchthat upon the production of the desired fluid temperature signal fromany one of them, the others are inoperative to produce a signal to thecomparison means. Thus, the thermistor circuit is cooperative with onlyone of the temperature selection circuits at any given time.

BRIEF DESCRIPTION OF THE DRAWING The single FIGURE of the drawing is aschematic diagram of the temperature controller according to the instantinvention.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring to the FIGURE atemperature controller for an industrial washing machine I is shown ashaving a regulated DC power supply 2. first circuit means comprising areference signal circuit 4. selector switch means 6. second circuitmeans comprising temperature sensing and indicating means 8. thirdcircuit means comprising a comparison circuit II). and water valvecontrol means I2. The DC power supply 2 is connected to a source of ACpower (not shown) \ia the lines LI and L2. The DC power supply 2includes a transformer I4. a rectifier comprising diodes DI. D2. D3 andD4 and filter capacitors 24 and 26. A voltage regulator 28 is also partof the regulated DC power supply 2 and provides a positivet+l andnegative(-) DC voltage of an appropriate level respectively to the lines30 and 32. The voltage regulator 28 is of a type well known in the artand consequently will not be discussed in detail.

The reference signal circuit 4 comprises three signal circuitsrespectively designated 40. and 60. The signal circuit 40 comprises atransistor OI and a biasing network comprising capacitor CI. diode D5and resistors RI, R2. R3 and R4, The signal circuit 40 also includes areference voltage network comprising resistor R5. variable resistor R6,diode D6 and output terminal a between resistor R6 and the collector oftransistor OI. The signal circuit 50 comprises a transistor 02 and abiasing network comprising capacitor C2. resistors R7, R8. R9 and RIO.The signal circuit 50 also includes a reference voltage networkcomprising resistor RII, variable resistor R12. and output terminal bbetween resistor R12 and the collector of transistor 02. The signalcircuit comprises a transistor ()3 and a biasing network comprisingcapacitor C3, and resistors R13, R14, R15. and R16. The signal circuit60 also includes a reference voltage network comprising resistor RI7,variable resistor R18. and output terminal between resistor R18 and thecollector of transistor 03. The reference signal circuit 4 furtherincludes a blocking circuit comprising a resistor R2] and diodes D6, D8,and DIO all having their cathodes connected together at junction f. Ascan be seen in the FIGURE, the anodes of diodes D6. D8 and D10 arerespectively connected to output terminals a, h, and c of the signalcircuits 40, S0, and 60. The cathodes of diodes D6, D8 and D10 areconnected through resistor R21 to line L2. Also, a line 76 is connectedbetween the junction fand the comparator for applying the signalappearing at any one of the terminals a. h. or c to the comparison meansII).

The selector switch means 6 comprises switches 34, 36, and 38. Whenthese switches are in their full line positions as shown in the FIGURE.they are in series with the line LI connected to the AC power source. Ifany of the switches 34. 36, or 38 is switched to the dashed lineposition as shown in the FIGURE the AC power source is connected to oneof the signal circuits 40, S0 or 60. The switches. 34, 36, and 38 areeach in different tracks ofa card programmer (not shown) that is used tocontrol the formula and cycles of the industrial washing machine 1. Sucha card programmer is well known in the art and will not be describedherein.

The temperature sensing and indicating means 8 includes a constantvoltage supply circuit comprising zener diode 72 and resistor R19. Athermistor 74, a temperature indicating meter 80 and a resistor R areconnected in series to a terminal between the zener diode 72 and theresistor R19. The thermistor 74 is in contact with water in the washingmachine 1 and has an inverse temperature-resistance characteristic wellknown in the art. The junction d between thermistor 74 and resistor R20is connected to the comparator 90. The thermistor 74 and meter 80 takentogether and resistor R20 form a voltage divider which provides avoltage signal level to the comparator 90 which is depen dent upon theresistance of the thermistor 74 and representative of the temperature ofthe water in the washing machine 1. If the temperature of the water inthe washing machine 1 is low, the resistance of the thermistor 74 willbe high so that the voltage signal level at the terminal d to thecomparator 90 will be at a low level relative to the positive voltage online 30. When the temperature of the water in the washing machine 1 ishigh. the resistance of the thermistor 74 is low so that the voltagesignal level at terminal (I at a higher level and closer to the voltagelevel on line 30. The meter 80 will visually indicate the watertemperature in response to the signal generated as the resistance of thethermistor 74 varies.

The comparison means 10 includes a comparator 90 connected to thepositive DC line and the negative DC line 32 and having inputs connectedto lines 76 and 78. The comparison means 10 also includes a transistorQ4. a resistor R22 connected between the line 30 and the collector oftransistor 04 and a resistor R23 con ncctcd between the base oftransistor 04 and an output of comparator 90. A transistor OS isconnected between the base of transistor Q4 and the AC power source lineL2 for the purpose of clamping the negative voltage present at the baseof O4 to a safe value.

The water valve control means 12 includes a control relay coil 92, acontrol relay coil 94 and a triac 96. Also included as part of the watervalve control means 12 is a resistor 98 and a capacitor 100 for shuntingline voltage transicnts around the triac 96 and a thyrcctor 102 foradditional surge voltage protection. As shown in the FIGURE, the controlrelay coil 94 is connected in scrics with the switches 34, 36, and 38between lines L1 and L2. The control relay coils 92 and 94 each havecontrol contacts (not shown) which control the hot and cold water valves(not shown) and which may be located in the washing machine 1. Thecontrol connection of their contacts by the relay coils 92 and 94 isrepresented by the dashed lines between the coils and the washingmachine 1 the the FIGURE. The arrangement of the contacts is such thatwhen switches 34, 36, and 38 are in their full line positions as shownin the F10- URE, control relay 94 will be energized and its contactswill be positioned such that the contacts of control relay 92 will haveno control over the water valves. The arrangement and operation of thecontrol relay contacts and the water valves is well known in the art andtherefore are not shown in the drawing and will not be further discussedherein.

ln the operation of the temperature controller, when all of the switches34, 36, and 38 are in their full lines positions, the control relay coil94 will be energized and the control relay coil 92 will have no controlover the hot and cold water valves of the washing machine 1. in thiscondition, the circuits through the signal circuits 40, S0 and 60between line L2 and line L] are open. However, the circuit between lineL2 and posi tive DC line 30 through resistors R2, R3. R4 and capacitorC] in signal circuit 40 is closed. The circuit between linc L2 and line30 through resistors R8, R9. R 10 and capacitor C2 in the signal circuit50 is also closed as is the corresponding circuit in signal circuit 60.ln this condition, the circuit components R2, R3, R4 and C1 in signalcircuit 40 have values such that the signal at the base of transistor 01is sufficient to forward bias it. When transistor O1 is conductive itcompletes a circuit between line 30 and line [.2 through resistor R5,resistor R6 and the collector-emitter of transistor 01. Thus, a signalnormally appears at the output terminal a which is equal to thecollector-emitter saturation voltage ofOl, considering the voltage online L2 as a reference voltage. This collector-emitter saturationvoltage is less than that required to forward-bias diode D6. The signaltherefore on line 76 to the comparator is very close to zero withrespect to line L2. The operation of the remaining signal circuits 50and 60 is identical to that of signal circuit 40 when switches 36 and 38are in their full line positions and therefor the operation of signalcircuits S0 and 60 during this condition of the temperature controllerwill not be also describedv The switches 34, 36, and 38 are normallycontrolled by the card programmer such that only one at a time of theswitches 34, 36, and 38 is switched to its dashed line condition. Forpurposes of convenience, the dashed line condition of each switch willhereafter be referred to as the closed condition. Each one of theswitches 34, 36, and 38 is utilized during a different one of theoperation cycles of the washing machine. Thus, placing one of theswitches in its closed condition permits water temperature controlduring the operation cycle associated with the closed switch. With theswitch 34 in its closed condition, a circuit is completed throughcapacitor C1. resistor R1 and diode D5 between lincs L1 and L2. Thus,during each negative half cycle ofthe AC power source on line Ll,capacitor C1 is charged to a negative value which also appears at thebase of transistor 01. When capacitor C1 reaches a sufficient negativevoltage level, transistor 01 ceases to conduct. the level of the outputvoltage signal at terminal u will rise closer to the positive voltage online 30 and this voltage level will appear through diode D6 on line 76at the input of comparator 90. The level of this output voltage signalcan be selected at a desired value by adjusting the variable resistorR6. The resistor R6 thus permits selection of the water temperaturewhich is desired during operation of the washing machine 1 operationcycle associated with the signal circuit 40 and switch 34. Therelatively positive signal level appearing at terminal 0 also appears atjunction f and therefore at the cathodes of the diodes D8 and D10respectively in the signal circuits 50 and 60. Since the normal voltagesignal level at the anodes of diodes D8 and D10 is close to thereference voltage on line L2, diodes D8 and D10 will be reversed biasedso that terminals b and 0 will be isolated from the comparator 90.

Assuming that the water in the washing machine 1 is at a low temperatureat the start of a washing machine operating cycle when the switch 34 isplaced in its closed condition, the thermistor 74 will have a highresistance value. Accordingly, the voltage signal level representativeof the water temperature on line 78 to comparator 90 will be at a lowlevel. Also assuming that the desired water temperature as selected byresistor R6 is higher than the actual water temperature at the start ofthe operation cycle, the level of the signal on line 76 to comparator 90is higher than the signal on line 78. In this condition of thetemperature controller, the comparator 90 produces an output throughresistor R23 to the base of transistor Q4 sufficient to maintaintransistor 04 in a non-conductive condition. When transistor ()4 is notconducting, gating current for the triac 96 is obtained through resistorR22 from line 30. Thus, triac 96 is conductive so that relay coil 92 isenergized. When energized, relay coil 92 controls its contacts to openthe hot water valve and thereby raise the temperature in the washingmachine. When the water reaches a temperature higher than the desiredtemperature, the resistance of thermistor 74 becomes low so that thelevel of the signal on line 78 to the comparator 90 becomes higher thanthe level of the signal on the line 76 to the comparator 90 from theterminal a. The comparator 90 will then produce a positive output signalto the base of transistor 04 which is sufficient to cause transistor O4to conduct and shunt the gating current to the gate of triac 96. Triac96 then becomes non-conductive so that control relay coil 92 isdeenergized. When the relay coil 92 is deenergized, the washing machinecold water valve is opened and cold water enters the machine until thethermistor 74 resistance changes to a value which results in the levelof the signal on line 78 to comparator 90 again being lower than thelevel ofthe signal on line 76. The output of comparator 90 then againchanges to a value sufficiently negative to cut off conduction oftransistor 04 and permit gating of triac 96 and resultant admission ofhot water to the washing machine. It can thus be seen that as thetemperature of the water in the washing machine varies about thepreselected temperature point, the thermistor 74 will change itsresistance value to provide a signal to the comparator 90 and thecomparator 90 produces an output which will cause hot or cold water tobe added to the washing machine to change the tetnperature of the waterin the direciton of the desired set temperature. Further, throughout theentire water temperature adjusting operation the meter 80 will beindicating the water temperature to thereby provide a check on theproper operation of the controller.

The other signal circuits 60 and 70 cooperate with the thermistor 74 andthe comparison means 10 in a manner similar to that of signal circuit40. The only dif ference in operation of signal circuits 5" and 60 isthat their respective variable resistors R12 and R18 may be set fordifferent desired water temperatures and therefore the level of theoutput reference signal at terminals h and r to line 76 will bedifferent and a different signal level on line 78 to comparator will berequired to cause a change in the output signal level ofthe comparator90 to the base of transistor ()4.

While only one specific embodiment of the invention has been shownherein, it will be realized that many modifications thereof are feasiblewithout departing from the spirit and scope ofthe invention. forexample. the disclosed temperature controller could be used in any typeof apparatus utilizing a fluid or fluids during more than one operatingcycle. Also, the entire controller can readily be modified to utilize aDC supply voltage without departing from the scope of the invention Itis accordingly intended that the scope of the invention is not to belimited to the specific embodiment disclosed. 1 claim: 1. A controlcircuit for controlling the temperature of a fluid in an apparatushaving a plurality of operation cycles comprising:

first circuit means comprises a separate signal circuit for each one ofsaid operation cycles, each signal circuit having an output signalcondition and producing a predetermined first signal representative of adesired fluid temperature during each one of said operation cycles whenin said condition, no more than one of said signal circuits having anoutput signal condition at any given time, the other signal circuitshaving a normal signal condition, said first circuit means includesblocking circuit means responsive to the output signal condition of saidone of the signal circuits to block the normal signal condition of theother signal circuits;

second circuit means for producing a second signal representative of theactual fluid temperature and indicating said actual temperature duringeach one of said operation cycles; and

third circuit means connected to said first and second circuit means andbeing responsive to the first and second signals for comparing thelevels of said first and second signals during each one of saidoperation cycles and producing an actuating signal when the levels ofsaid first and second signals have a predetermined relationship.

2. The combination according to claim 1 wherein:

each signal circuit has an output terminal; and

said blocking circuit means comprises a different diode connectedbetween each signal circuit and the third circuit means, all diodesbeing commonly connected together between said diodes and the thirdcircuit means.

1. A control circuit for controlling the temperatUre of a fluid in anapparatus having a plurality of operation cycles comprising: firstcircuit means comprises a separate signal circuit for each one of saidoperation cycles, each signal circuit having an output signal conditionand producing a predetermined first signal representative of a desiredfluid temperature during each one of said operation cycles when in saidcondition, no more than one of said signal circuits having an outputsignal condition at any given time, the other signal circuits having anormal signal condition, said first circuit means includes blockingcircuit means responsive to the output signal condition of said one ofthe signal circuits to block the normal signal condition of the othersignal circuits; second circuit means for producing a second signalrepresentative of the actual fluid temperature and indicating saidactual temperature during each one of said operation cycles; and thirdcircuit means connected to said first and second circuit means and beingresponsive to the first and second signals for comparing the levels ofsaid first and second signals during each one of said operation cyclesand producing an actuating signal when the levels of said first andsecond signals have a predetermined relationship.
 2. The combinationaccording to claim 1 wherein: each signal circuit has an outputterminal; and said blocking circuit means comprises a different diodeconnected between each signal circuit and the third circuit means, alldiodes being commonly connected together between said diodes and thethird circuit means.